1,537,244 research outputs found
Comment on "Modified Coulomb Law in a Strongly Magnetized Vacuum"
This is a comment on Phys. Rev. Lett. 98, 180403 (2007) [arXiv:0704.2162].Comment: 1 page, comment on arXiv:0704.2162, published versio
Impurity-doping induced ferroelectricity in frustrated antiferromagnet CuFeO2
Dielectric responses have been investigated on the triangular-lattice
antiferromagnet CuFeO2 and its site-diluted analogs CuFe1-xAlxO2 (x=0.01 and
0.02) with and without application of magnetic field. We have found a
ferroelectric behavior at zero magnetic field for x=0.02. At any doping level,
the onset field of the ferroelectricity always coincides with that of the
noncollinear magnetic structure while the transition field dramatically
decreases to zero field with Al doping. The results imply the further
possibility of producing the ferroelectricity by modifying the frustrated spin
structure in terms of site-doping and external magnetic field.Comment: 4 pages, 4 figure
Coupled oscillators and Feynman's three papers
According to Richard Feynman, the adventure of our science of physics is a
perpetual attempt to recognize that the different aspects of nature are really
different aspects of the same thing. It is therefore interesting to combine
some, if not all, of Feynman's papers into one. The first of his three papers
is on the ``rest of the universe'' contained in his 1972 book on statistical
mechanics. The second idea is Feynman's parton picture which he presented in
1969 at the Stony Brook conference on high-energy physics. The third idea is
contained in the 1971 paper he published with his students, where they show
that the hadronic spectra on Regge trajectories are manifestations of
harmonic-oscillator degeneracies. In this report, we formulate these three
ideas using the mathematics of two coupled oscillators. It is shown that the
idea of entanglement is contained in his rest of the universe, and can be
extended to a space-time entanglement. It is shown also that his parton model
and the static quark model can be combined into one Lorentz-covariant entity.
Furthermore, Einstein's special relativity, based on the Lorentz group, can
also be formulated within the mathematical framework of two coupled
oscillators.Comment: 31 pages, 6 figures, based on the concluding talk at the 3rd Feynman
Festival (Collage Park, Maryland, U.S.A., August 2006), minor correction
Gauge-Higgs Unification and Quark-Lepton Phenomenology in the Warped Spacetime
In the dynamical gauge-Higgs unification of electroweak interactions in the
Randall-Sundrum warped spacetime the Higgs boson mass is predicted in the range
120 GeV -- 290 GeV, provided that the spacetime structure is determined at the
Planck scale. Couplings of quarks and leptons to gauge bosons and their
Kaluza-Klein (KK) excited states are determined by the masses of quarks and
leptons. All quarks and leptons other than top quarks have very small couplings
to the KK excited states of gauge bosons. The universality of weak interactions
is slightly broken by magnitudes of , and for
-, - and -, respectively. Yukawa couplings become
substantially smaller than those in the standard model, by a factor |\cos
\onehalf \theta_W| where is the non-Abelian Aharonov-Bohm phase
(the Wilson line phase) associated with dynamical electroweak symmetry
breaking.Comment: 34 pages, 7 eps files, comments and a reference adde
Measurement and Calibration of A High-Sensitivity Microwave Power Sensor with An Attenuator
In this paper, measurement and calibration of a high-sensitivity microwave power sensor through an attenuator is performed using direct comparison transfer technique. To provide reliable results, a mathematical model previously derived using signal flow graphs together with non-touching loop rule analysis for the measurement estimate (i.e. calibration factor) and its uncertainty evaluation is comparatively investigated. The investigation is carried out through the analysis of physical measurement processes, and consistent mathematical model is observed. Later, an example of Type-N (up to 18 GHz) application is used to demonstrate its calibration and measurement capability
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